The need to establish the relative positions of certain movable elements of a photographic camera system--for example, the lens and copyboard, relative to the film plane--and the requirement to be able to return each element precisely to a predetermined position relative to its associated elements, has occupied the attention of designers in the photographic field for many decades.
As early as Feb. 9, 1875, S. L. Bergstresser (U.S. Pat. No. 159,536 entitled "Camera") disclosed a belt and clamping device capable of adjusting and maintaining the position of the lens carrier of a camera relative to the associated image plane. On June 8, 1897, O. Linley patented a copying camera stand (U.S. Pat. No. 584,182 entitled "Copying Camera Stand") in which motion between the lens and copyboard, relative to the emulsion plane, is controlled by a system which includes a travelling nut and leadscrew, and a motion-limiting stop associated with a calibrated micrometer-screw adjusting means.
The concept of providing a precision dial indicator and incremental mounting means for use in measuring relative motion on machine tools, such as lathes and the like, is found in U.S. Pat. No. 2,458,344, issued to R. S. Carroll on Jan. 4, 1949, entitled "Precision Dial Indicator Mounting for Machine Tools". This device makes possible a quick change in the setting of the dial indicator for different depths or lengths of cut, and enables the major units in which the cut is measured to be accommodated by movement of the indicator bodily in the direction of the cut, while the desired fraction of the major unit is displayed by movement of the stem of the dial indicator itself. A refinement of the foregoing positioning technique appears in U.S. Pat. No. 3,274,689 issued on Sept. 27, 1966, to A. K. Schott entitled "Gaging Apparatus for a Machine Tool", wherein a single assembly containing a dial indicator may be slid along a horizontal bar having a series of aligned locating holes incrementally disposed along its length. The indicator assembly can be engaged and locked to any selected hole by means of a locating pin or plug, whereupon the dial indicator will display whatever relative motion takes place between its spindle and the workpiece.
Finally, Blatherwick (U.S. Pat. No. 3,739,479 issued June 19, 1973, entitled "Camera Carriage Precision Positioning System") shows a camera-positioning system which is somewhat similar to the Schott device in that each of several movable elements of the camera is provided with a movable carriage containing a dial indicator gauge capable of being pivoted vertically about a horizontal axis into, or out of, engagement with a precise, incrementally-notched horizontal bar fixedly mounted and extending along the length of the camera track. When the assembly is engaged with the bar, the dial indicator displays the position of the movable carriage between adjacent incremental notches.
There are two general types of camera-positioning systems currently in use. One type of system uses a scale tape connected to a gauge having gradations in percent of the size of the object to be photographed. The user of such a system moves the pointer of the gauge to the desired percent of size, and uses the scale tape to correctly position the camera means. While this device is relatively inexpensive and time efficient, the system's accuracy is relatively limited.
The second type of system employs an accurately machined lead screw for each carriage that is connected to a counter and a vernier dial. To accurately position the camera, the counter and dial are set to the numbers determined from a chart or from an equation. Although this system allows for relatively very accurate measurements and permits accurate repetition of a desired distance, the device is relatively expensive and time consuming to employ.
Thus, it is apparent that there is a need in the art for a camera-positioning device which is relatively inexpensive, can be quickly employed, and which is highly accurate as to the distances between the camera lens carried by the camera-positioning device and the object to be photographed.
This invention fulfills this need and other needs apparent to the skilled artisan in the relevant art once given the following disclosure: